Please refer to FIGS. 1A, 1B and 1C. The steps of a process of assembling a camera module 1 according to prior art will be illustrated as follows.
First of all, as shown in FIG. 1A, a composite printed circuit board 11 and an image sensing chip 12 are provided. The composite printed circuit board 11 includes a first rigid printed circuit board 111, a second rigid printed circuit board 112 and a flexible printed circuit board 113, which is sandwiched between the first rigid printed circuit board 111 and the second rigid printed circuit board 112. A perforation 114 is formed in the composite printed circuit board 11. A signal terminal 111A is formed on a surface of the first rigid printed circuit board 111 of the composite printed circuit board 11. The image sensing chip 12 includes an image sensing region 121 and a contact pad 122, which is arranged outside the image sensing region 121 and corresponding to the signal terminal 111A. A conductive bump 13 is formed on the contact pad 122.
Next, as shown in FIG. 1B, the signal terminal 111A of the first rigid printed circuit board 111 and the conductive bump 13 of the image sensing chip 12 are aligned with each other, and then the image sensing chip 12 is laminated with the composite printed circuit board 11. Consequently, the image sensing chip 12 and the composite printed circuit board 11 are electrically connected to each other.
For isolating the image sensing chip 12 from the adverse environmental conditions such as humidity, dust and the like, an underfill 14 is formed on the periphery of the image sensing chip 12, as can be seen in FIG. 1C.
The process of assembling the camera module 1 as shown in FIGS. 1A, 1B and 1C is disclosed for example in Taiwanese Patent No. 543,925, and the contents of which are hereby incorporated by reference.
Please refer to FIG. 1C again. For preventing isolating the image sensing chip 12 from humidity or dust, it is necessary to reserve an operative area W1 on the composite printed circuit board 11 so as to apply the underfill 14. The extended length W of the composite printed circuit board 11 resulting from the operative area W1 is still adverse to minimization of the overall camera module 1.
In views of the above-described disadvantages resulted from the prior art, the applicant keeps on carving unflaggingly to develop a camera module and an assembling process thereof according to the present invention through wholehearted experience and research.